Little Moreau #1 Reservoir Report
Nearby: Little Moreau #2 Little Moreau #3
Last Updated: December 13, 2025
Little Moreau #1 is a state-owned earth dam located in Dewey, South Dakota, along the picturesque Little Moreau River.
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Summary
Built in 1933 by the Works Progress Administration (WPA), this dam stands at a height of 30 feet and has a storage capacity of 507 acre-feet. With its uncontrolled spillway and low hazard potential, it serves as a vital water resource for the region, providing irrigation and flood control benefits to the surrounding area.
Managed by the South Dakota Department of Agriculture and Natural Resources, Little Moreau #1 is subject to regular state inspections and enforcement to ensure its structural integrity and compliance with regulations. Despite its moderate risk rating, the dam has not been assessed for its condition, emergency action plan preparedness, or risk management measures. With its historical significance and continued importance in water resource management, Little Moreau #1 remains a key piece of infrastructure in the region, contributing to the overall resilience of the local ecosystem and community.
As climate change continues to impact water resources and weather patterns, the role of dams like Little Moreau #1 becomes increasingly crucial in mitigating risks and adapting to changing conditions. With its strategic location and operational history, this dam stands as a testament to the enduring importance of water resource management in the face of evolving climate challenges.
Year Completed |
1933 |
Dam Length |
662 |
Dam Height |
30 |
River Or Stream |
LITTLE MOREAU RIVER |
Primary Dam Type |
Earth |
Hydraulic Height |
30 |
Drainage Area |
51 |
Nid Storage |
507 |
Outlet Gates |
None |
Hazard Potential |
Low |
Foundations |
Soil |
Nid Height |
30 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Moreau R Near Whitehorse Sd
|
35cfs |
Grand R At Little Eagle Sd
|
47cfs |
Oak Cr Near Wakpala Sd
|
10cfs |
Cedar Creek Nr Raleigh
|
20cfs |
Moreau R Near Faith Sd
|
14cfs |
Cannonball River Nr Raleigh
|
40cfs |
Dam Data Reference
Condition Assessment
SatisfactoryNo existing or potential dam safety deficiencies are recognized. Acceptable performance is expected under all loading conditions (static, hydrologic, seismic) in accordance with the minimum applicable state or federal regulatory criteria or tolerable risk guidelines.
Fair
No existing dam safety deficiencies are recognized for normal operating conditions. Rare or extreme hydrologic and/or seismic events may result in a dam safety deficiency. Risk may be in the range to take further action. Note: Rare or extreme event is defined by the regulatory agency based on their minimum
Poor A dam safety deficiency is recognized for normal operating conditions which may realistically occur. Remedial action is necessary. POOR may also be used when uncertainties exist as to critical analysis parameters which identify a potential dam safety deficiency. Investigations and studies are necessary.
Unsatisfactory
A dam safety deficiency is recognized that requires immediate or emergency remedial action for problem resolution.
Not Rated
The dam has not been inspected, is not under state or federal jurisdiction, or has been inspected but, for whatever reason, has not been rated.
Not Available
Dams for which the condition assessment is restricted to approved government users.
Hazard Potential Classification
HighDams assigned the high hazard potential classification are those where failure or mis-operation will probably cause loss of human life.
Significant
Dams assigned the significant hazard potential classification are those dams where failure or mis-operation results in no probable loss of human life but can cause economic loss, environment damage, disruption of lifeline facilities, or impact other concerns. Significant hazard potential classification dams are often located in predominantly rural or agricultural areas but could be in areas with population and significant infrastructure.
Low
Dams assigned the low hazard potential classification are those where failure or mis-operation results in no probable loss of human life and low economic and/or environmental losses. Losses are principally limited to the owner's property.
Undetermined
Dams for which a downstream hazard potential has not been designated or is not provided.
Not Available
Dams for which the downstream hazard potential is restricted to approved government users.
Little Moreau #1